1. The second snowfall

After the first snowfall of winter can be a problem especially sliding snow avalanches, Thus avalanches which slide down the steep slopes and smooth. After the second significant snowfall occurs, then the upper range of the slide plate avalanche. Slab avalanches are characterized primarily as avalanches and ski at least 95% may be a fatal avalanche accident. The snow profile may under certain circumstances, eg getting up between the first snow and the second layer of snow considerably unstable, which can then be quite easily disrupt. And the second snowfall this plays an important role mainly because, that this new snow partially disguises or imminent danger, and also at this moment mostly still think so much snow, enough to form a carrier layer. Most of the problems of this kind occur in high (>2000 m) and alpine (>3000 m) shadymsteep slopes. Attention, this type of avalanches can also be very difficult to detect in a timely manner!

2. Moving snow

Snow slides, of course, especially on steep slopes and smooth rocks. The cracks can be formed within the snow profile. Therefore, they are clearly visible and at times can be several meters deep. Unlike the older and, unfortunately, difficult vyvratitelných advice, these cracks are described rather as a stabilizing (release tension), today's professional opinion, rather the opposite impact, with respect to possible avalanche slide. The crack across the snow above shows the possibility of a landslide moving avalanches of snow, but says nothing about, if and when such a snow avalanche as meat really really moving snow slides. Moving snow avalanches are due to landslide the worst moment of predictable avalanches, as they may also fall in the generally stable snow conditions at any time day or night, as in the coldest, as well as the hottest day of winter. Moreover, the moving snow avalanches are released spontaneously and not primarily due to additional load.

3. Rain

Rain is a classic warning sign, and especially in avalanche prevention. This is because, on the one hand brings snow cover any additional load on the other hand, leads mainly to the rapid loss of strength snow profile. Avalanche danger is, therefore, clearly destined to! Rain can occur in any part of the winter. A huge advantage of this situation lies primarily in, that no other type of avalanche danger is not just easier to recognize.

4. Cold for heat / heat after cool

Too long in the avalanche took the issue of opinion in the classroom, the large temperature difference during nasněžení (It does not matter whether the heat or cool backwards) positive effect on the avalanche situation. This happens only under certain assumptions. Mostly, however, has such a negative temperature difference, because it supports the conversion výstavbovou (accretion of crystals) within the snow profile. Usually, this will create a thin layer and completely unstable. This treacherous layer can often be traced to the slopes with southern exposure. Her deceit is great but especially in the, that this thin layer is unstable and not immediately after nasněžení still in the snow profile available and begin to build up only over the following days.

5. Snowfall (but the wind) after a long cold period

Classic between avalanche events. After a long cold period starts snowing. In addition, strong winds, which correspondingly moves the new snow. In a very short time a very tricky for skiers avalanche situation. The same can happen even if, when after a long period of cold blowing "just” very strong wind, without snow. The fundamental problem, which occurs at the moment, is that, that on the leeward slopes of the stores fresh and above all wind predominantly snow, which lies on the unstable snow blanket the old profile, who is most at this moment consists primarily of a so-called malicious. floating snow. Fresh windblown snow and old snow so unstable is very difficult to connect with each other. Snow then waits for easy distortion even at a slight additional load.

6. Cold and fluffy new snow combined with wind

"Wind is the builder of avalanches”, this classic phrase from Wilhelm Paulckeho from the thirties are also unchanged today. Wind affects, as falling, as well as the snow has dismounted and is one of the essential factors constituting the avalanche. In loose, new dry snow wind ALWAYS leads to relocation and thus to increase avalanche danger! The colder the moving snow, it responds sensitively to any other additional load, because of his increasing frailty . This type of risk is different from the type number of avalanches 5 thereby, the cold and snow there will be no loose during prolonged periods of cold, but rather a very short time and suddenly. The situation goes something like this: snow without wind effect shortly before the cold temperatures and only later begins to blow and the wind is gathering momentum. This is the type of avalanche danger, which can usually recognize a really good.

7. Places with little snow during the snow-rich winters

In winters rich in snow, under normal circumstances becomes considerably less than the avalanche disaster in winters with a lack of snow, because construction is preferable to snow. Still, can also be observed in snow-rich winters regularly phenomenon, on the basis of existing weather conditions are very wind exposed slopes relatively poor snow. Accordingly, there are far more suited song snow profile, and the more likely they are released avalanche winter tourists right there.

8. Snow surface hoar

Surface hoar is one of the most beautiful species of snow at all and does not hide itself, yet no significant risk. Ale v Moments, when at this very unstable surface layer of new snow invades, situation is fundamentally changing. And even if, that a new layer of snow lying on these fragile crystals, are already interconnected. This is a very treacherous situation, mainly because, the surface layer of frost in the snow profile very poorly tracing.

9. Snowy barley

Unstable layers within the snow cover in avalanche courses are often compared to ball bearings. Indeed, but this picture is probably only suitable for barley. Krupka is a form of solid precipitation sphericity, occurring during storm showers mainly in the spring. It is easy to imagine, what happens, when the layer of freshly fallen grouts predominantly snow begins to store. If they encounter in the snow profile, are a clear guide for you in your next decision. But barley is mostly absent on the ground in large quantities. And the wind also moves the slope barley very irregularly and with it another major problem, because they do not, and a detailed examination of snow profile, not encounter. It's absolutely insidious affair, Fortunately, that only leads to short-term problems.

10. Spring situations

A particular challenge for skialpinism, skiers, tourists, themselves but also for a spring avalanche forecasters. Rarely, lies the concept of "safe” and "dangerous” time situation so close to each other, just as the spring. Rarely is the bandwidth of degrees issued by avalanches during one single day so great. On the one hand, it is hardly possible avalanche danger ever so easy to assess, than just the stable spring conditions firnových. On the other hand, are also hardly ever recorded during the winter and large landslides avalanches, just as critical during the spring situation.
Apart from the composition of the snow profile has a decisive role in alternating cycles of freezing and thawing (AC blending). This process is dependent on the temperature, humidity, effects of radiation and of course the wind. For winter tourists have time to discipline themselves and hike very early flexibility in planning hikes price of the current conditions of life.

Translation – Viktor Kořízek, Lezec.cz